I. Introduction to the butt welding connection and socket welding connection of the valve:
The welding connection method of the valve is divided into two kinds of butt welding connection and socket welding connection, which are code-named "6" in the national standard GB/T308 model preparation.
1, butt welding connection: butt welding connected valve has a bevel groove, groove size according to the outer circle and inner diameter of the pipeline processing. The processing method of valve welding groove is detailed in the national standard GB/T12234, the general valve groove has 3 angles according to the standard, but the small diameter valve below 50 sometimes has only one Angle. Butt welded connection All valves are available.
2, socket welding connection: socket welding connection is to extend the pipe into the valve body for welding, it looks like an internal screw valve but there is no screw, and the inner diameter of the socket is 1~2mm larger than the outer circle of the pipe. Most of the valves connected by socket welding are forged steel gate valves, globe valves and check valves below 50 caliber, the kind of black skin (a black oxidation and rust prevention surface treatment process, and now there is phosphating treatment, the color is gray). Design and manufacture standard API602 and JB-T7746 compact steel valves.
Second, the valve butt welding connection and socket welding connection comparison:
1, socket welding can not be X-ray detection, you can do magnetic powder or penetration detection. After welding, the part of the pipe inserted into the valve body will leave a gap, so the pipe system used for the gap corrosion sensitive medium and the pipe system with high cleaning requirements should not be welded with socket.
2, the butt welding can be done ray, magnetic powder or penetration testing, welding strength, stress and other analysis of the butt is better than socket welding, and can be strictly tested.
Therefore, the high-demand conditions that can not accept a defect are selected for butt welding connection, which is convenient for 360-degree detection. Socket welding can be used for valves up to 2500LB and up to DN50.